Description ALL BIRDS Have more blackish upperparts (not so dark brown, as in Audubon's) and mainly white underparts, although wing margins are dark.

Dimensions Length: 12 1/2-15" (32-38 cm)

Habitat Summer visitor to North Atlantic, present mainly Jun-Sep; winters in South Atlantic. Breeds on remote islands, mainly in northeast Atlantic but recently in Canada too, in small numbers. Fairly widespread in offshore Atlantic waters during spring and summer and favors cooler waters than Audubon's.

Observation Tips Sometimes seen from whale-watching trips operating out of New England ports.

Range Eastern Canada, New England, Mid-Atlantic, Southeast

Voice Silent at sea but at breeding colonies weird, strangled coughing calls are uttered after dark by nesting birds.

Discussion Appreciably larger than Audubon's and separable by noting the white undertail coverts, relatively shorter tail, and greater extent of white on underwings. Contrast between dark upperparts and mainly white underparts are revealed as it banks and glides. Invariably seen at sea flying low over the water on stiffly held wings. Typically seen in sizeable groups. Sexes are similar.